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Meat And Its Products

( Originally Published 1939 )



TECHNOLOGY

Although the flesh of fish and fowl is meat just as truly as that of cattle, swine, sheep, and goats, the term meat is generally restricted to the flesh of the latter animals. The amount of edible cuts from dressed-out carcasses averages about 55 percent for steers, about 50 percent for sheep, and about 80 percent for swine. All the remainder must be disposed of in some way to preclude its being a public nuisance. The high content of nitrogen in this waste gives it value as a fertilizer, but this is its cheapest outlet. Research has been finding new uses for many of the parts so that now a profitable meat-packing company produces prepared meat products, and a long list of specialty products such as different grades and varieties of hides, gelatin, glandular extracts, lard and other cooking fats, oleomargarine, and some-times allied lines like butter, eggs, and miscellaneous canned foods. The production of meat has progressed beyond the facilities of the local butcher merely to slaughter animals and dress out their meat, and has become a highly technical industry, based on the latest findings of biological and chemical science, and dependent for its existence on expert selection and purchase of animals, technological control of the packing-house operations, forceful merchandising, and ample financing.

Inspection. The preparation of meat is conducted in establishments which range in size from those of the small cooperative butchering abattoirs to huge plants which cover several acres. The capital investment covers a commensurate range. Generally, the large plants engage in interstate business, and this can be conducted only when the plant is under license to operate according to the inspection procedure of the U. S. Department of Agriculture. Some of the more progressive municipalities have enacted meat control ordinances and have patterned their inspection procedure on the federal model. Where such effective supervision obtains, the meat packer operates under a license from the control official. However, the U. S. Department of Agriculture estimates that only about 70 percent of the meat consumed in this country is manufactured under federal inspection. Only a few municipalities enforce an equally effective inspection.' The Federal Meat Inspection Service reported 2 that during the fiscal year ending June 30, 1934, more than 77,500,000 animals were slaughtered under the supervision of 2527 inspectors, and the resulting meat and meat food products were processed in 741 establishments, located in 255 cities and towns. Through these inspections, 312,731 animals and carcasses, together with 1,113,381 parts of carcasses, were condemned on account of 50 diseases or other unwholesome conditions. The cost was 6.1 cents for each animal slaughtered.

Ante-mortem inspection. Inspection of animals for slaughter be-gins while they are alive. Animals that are sick not only constitute a health hazard themselves but may infect other animals and their dressed meat. Excessive fatigue, overexcitement, bruises, broken bones, and other unnatural conditions bring loss to the packer. The examination of unfit animals on the hoof is called ante-mortem inspection, and these are tagged for special slaughter without contaminating the regular operations.

Post-mortem inspection. The animals are then driven into the packing house and diverted to the several departments which handle the respective stock. The details of slaughter and packing are some-what different for the several kinds of animals, but the principle is the same, namely, that slaughter must be as humane as possible, that dressing of the carcass must be done without contamination with offensive body discharges or infectious products, that the inspector him-self examine the condition of the carcass with its organs and glands for telltale signs of disease, that all parts that he condemns be actually treated as he directs, and that all the operations of the slaughter house be conducted under the detailed supervision of trained inspectors. Those parts of the animal which are found to be sound and wholesome are stamped "U. S. Inspected and Passed," with a special purple ink. Other parts may be found which need more detailed examination than can be given during the busy operations of the day. These are tagged for retention, and are sent to a special department for more leisurely inspection. Some parts may be judged to be edible under certain conditions, and are passed for sterilization under the regulations, whereas those parts which are not fit for food are marked "U. S. Inspected and Condemned." The former are sent to the chill rooms or cutting departments for subsequent cooking; the latter are sent to huge iron tanks for denaturing and sterilization under steam pressure, to be sold as fertilizer.

The openings and outlets of these condemnation tanks, as well as the rooms for retained parts, are kept under locks which can be opened only by inspectors. The check-up of all questionable parts, the disposition of the waste and condemned parts, and the stamping of the wholesome meat give the inspection service absolute control over the operations of the establishment, and assure the packing of only sound products.

The inspectors have small serially numbered cardboard tags, cut so that sections can be detached, each bearing the same number. As each part of a carcass is examined, the inspector attaches a section of the tag. Any condemned parts or those retained for further examination or special disposition can readily be traced through the plant, be-cause no plant operator is allowed to remove a tag unless permitted by the inspector, and all tags must be completely accounted for.

Slaughter. Animals are not fed before slaughter, but they are given plenty of water. They are well rested, and protected from excitement. Unless this care is exercised, the carcasses will not bleed well, and this is necessary to improve their keeping quality and appearance.

Cattle are driven singly into a small stall, too narrow for the animal to turn around. As soon as an animal enters, a door is dropped behind it to prevent its backing out. A workman stands on a plat-form outside the stall, and strikes the animal a hard blow on the head with a special weapon called a hammer. This "knocking," as it is called, renders the animal unconscious. A side wall of the stall is raised so that the animal rolls out onto the killing floor. A hind foot is shackled to a chain, and the animal is raised from the floor. The large blood vessels in the throat are quickly severed, and the carcass is allowed to bleed freely.

The orthodox Jewish religion requires that a special procedure be practiced in dressing meat. This is called Kosher meat, and is stamped in Hebrew characters. In this practice, the animal is not stunned. Its hind legs are shackled to a chain which raises the animal and turns it over so that its shoulders rest on the floor. Its head is forced back to stretch the tissues of the throat which is quickly cut to sever the windpipe, gullet, and blood vessels. The workman is known as a shochet. He must have a good character as certified by the rabbi, and possess special training for this work.

Pigs are usually shackled by their hind legs to a traveling belt.

This conveys them past the operator who "sticks" them in the throat to sever the blood vessels. The bleeding is completed as the animals are conveyed along the "bleeding" rail.

Sheep, lambs, and calves are slaughtered, usually without stunning, by cutting the throat transversely to facilitate complete bleeding and to sever the spinal cord. Sheep may be stuck on a rail like pigs.

Dressing. When bleeding is complete, the heads of cattle are severed, and the carcasses are lowered to the floor where they are propped on their backs for dressing. After the removal of the hides and organs, the carcasses are split along the backbones. The dressed sides of beef are washed, and then railed to the fore-cooler. This room has a temperature of about 45° F. during the period of slaughter when the box is filling up, but soon it is lowered to 40° F. The heat from the warm carcasses, together with the relatively large evaporation of moisture, would spoil the other meat in the chill room if the freshly dressed meat were immediately railed in.

The well-bled carcasses of hogs are conveyed to a tank of scalding water at a temperature of about 140° F. where they are immersed for about 6 minutes to loosen the hair. Automatic conveyors pass them through dehairing machines which remove the bristles by scrapers on flexible metal springs, enabling the blades to adjust themselves to the irregularities of the bodies. The last traces are removed by hand. The carcass is then swung by the hind legs to an overhead rail for dressing. The body is opened along the ventral median line, and the intestines are placed on adjacent inspection tables. In large establishments, a traveling belt conveys a line of pans or trays at the same rate that a chain conveys the carcass on the rail, thereby enabling the intestines to travel with the carcass, and maintain their identity. The inspectors examine the organs and glands, and route the parts to their proper destination. The carcass is finally split down the backbone, cleaned, stamped, and sent to the cooler.

Sheep and calves are dressed somewhat similarly, although the kidneys may not be removed from the calves and the skins are usually left on to improve the appearance.

Refrigeration. In the fore-cooler, the meat may lose as much as 1.5 to 2.0 percent of its weight in evaporation, dependent on the humidity, temperature, and condition of the carcass. When the temperature has dropped to about 40° F., the meat may be placed in the regular chill room which is maintained at a temperature of about 34-40° F. Sometimes, meat is frozen at temperatures of about 3-15° F. This may require about 6 days. When such meat is withdrawn for sale, it is defrosted by slowly thawing at chill-room temperatures in a good circulation of air. Such meat may be greatly harmed by the rupture of the cells and the freezing of the extractives. A large part of the extractives may be lost, when the meat is defrosted, by melting and dripping off. Such meat also spoils more quickly than that which has been held merely chilled at temperatures just above freezing.

Several varieties of mold and bacteria, sometimes markedly colored, grow on meat in storage. These may exert only a superficial effect or may penetrate the tissue and cause more or less spoilage. Sodium hypochlorite is an effective agent for general use in keeping a packing house in a good sanitary condition. Inasmuch as the presence of organic matter dissipates the strength of the solution, it is necessary to clean all equipment thoroughly. It is not a substitute for cleanliness but is an excellent supplement. All equipment that comes in contact with the meat should be rinsed with hot water, scrubbed with a detergent, and then rinsed or sprayed with this solution. It should be used throughout the plant, in the offices, halls, and stair-ways, locker-rooms, toilets, laundry, and restaurant, as well as in the meat-dressing and curing rooms. In strength of 0.4 percent solution, it not only kills the various organisms which cause spoilage but also sweetens the air and destroys bad odors.

A carbon dioxide content of 10-20 percent at a temperature of 32° F. is quite effective in arresting the formation of mold, and reduces the amount of bacterial spoilage.

Meat curing. When meat is treated with common salt, either by rubbing the dry salt over each piece or by soaking it in brine, the salt penetrates the tissue and draws moisture from the meat, making a pickle. The salt penetration is often hastened by pumping or injecting brine into the meat under pressure. The use of common salt alone imparts a dull gray color to the meat, but with sodium nitrate a bright red color is produced. The effective agent is sodium nitrite which is formed by the reduction of the nitrate. Sugar and sometimes spices are also added to give some special flavor and help preserve the product. The formulas differ greatly, but a typical one consists of 2 pounds of sugar, 3 pounds of salt, and 4 ounces of sodium nitrate (or 3/4 ounce sodium nitrite) for each 100 pounds of meat. After the meat has been given this cure, with several "overhaulings," for about 25 days at 38° F., it is soaked in water at 70° F. and dried. This treatment is best adapted for bacon and hams for smoking.

Smoked meat. Preservation by smoking is applicable only to meat which contains a relatively small amount of moisture, such as pickled meats or sausage which loses its water readily. Spoilage is inhibited by low content of moisture and by chemicals in the smoke. Different kinds of wood impart specific flavors. Hard woods are preferred, especially hickory. Smoking may be a slow process, requiring weeks at a temperature of about 70° F., or it may be speeded up to less than a day at about 160° to 200° F.; often it is conducted at about 110° to 125° F. Sometimes the flavor is imparted by dipping the meat into special solutions.

Sausage. Sausage is a mixture of various meat products, some-times with spices. It usually is encased in a light covering, which may be cloth, paper, natural casings of washed intestines, or artificial casings. The quality of sausage varies with the grades of meat of which it is manufactured. Sausage affords a good outlet for the tougher muscle meats, organs, connective tissue, and sometimes blood. Various spices are added, such as pepper, sage, onions, cinnamon, and cloves. Some sugar may be used, and usually some common salt and saltpeter. The various meat products are weighed into a flat sausage grinder, and chopped until the meat is finely comminuted. To reduce the heat and prevent spoilage during this operation, crushed ice is often added. When the desired consistency has been obtained, the flavoring ingredients are added, and thoroughly mixed. The batch is then forced under pressure into the cleaned casings. They are divided into links by giving a quick twist to the tube at regular intervals. The chains are hung on racks in the smoke house for several hours at a temperature of about 150° F. and then cooked in vats of water at about 170° F. Sausage may be marketed without casings. The materials are held together by a thin layer of coagulated protein. This is formed around the product when it is cooked in metal tubes. Artificial casings are also made from cellulose which can easily be removed before the sausage is eaten.

When the cheaper grades of meat products are used in the preparation of sausage, the cooking and smoking treatment causes a loss of moisture which imparts a shriveled, unsightly appearance. Various products are added to increase the binding power, as it is called, and hold the moisture. Soybean and cereal flours, starches, and particularly skim milk powder are the usual ingredients for maintaining this desired plumpness and juiciness. The federal regulations consider them to be adulterants whose presence must be declared on the labels; 3.5 percent is the maximum amount permitted.

Canning. The canning of meat is chiefly restricted to corned beef and potted meats. Corned beef is boiled for about 1 hour and then placed in the can. It is necessary to close the can so that the contents are under a good vacuum. This may be accomplished in a vacuum capping machine or by a special heat treatment in which the meat in the can is heated to steaming and capped immediately, so that on cooling the steam condenses to form the desired vacuum. After sealing, the cans are sterilized by heating in steam retorts under pressure. A 1-pound an may be heated at about 230° F. (110° C.) for 1˝ to 2 hours, depending on the previous treatment.

Potted meat is boiled, spread on shallow pans, heated, forced into cans, and processed (or sterilized) at 233° F. (112° C.) for about 11/2 hours. The method of handling the hot product insures that the closed can will contain a satisfactory vacuum.

Exemptions to inspection. The federal regulations allow exemptions from the regular official ante- and post-mortem inspection to retail butchers and retail dealers who supply their own customers with limited amounts of meat and meat food products. Each such dealer must apply for a certificate to accompany the shipment in interstate commerce. The exempted dealer must conform to the regulations which govern official establishments in regard to labeling, sanitation, and the use of dyes, chemicals, and preservatives.

Farm-killed carcasses and farm-manufactured meat food products may be shipped in interstate commerce, provided that the animals were killed and dressed on the farm and that the farmer furnishes a properly executed certificate to the carrier, certifying that the officially uninspected products were healthful and wholesome as food, and contain no added ingredient contrary to the regulations of the U. S. Department of Agriculture.

RELATION TO THE PUBLIC HEALTH

Composition. Fresh meats consist of about 50-70 percent water, about 20 percent protein, and about 1 percent mineral. The fat varies greatly, running from 10 to 20 percent in beef muscle cuts, less in veal, and more in sheep.

Nutritive value. Although man emerged from unrecorded antiquity on a diet consisting mostly of animal products, many persons think that meat food is harmful. The cuts of meat which are commonly used do not contain the organs, blood, bone, marrow, and other parts which were (and still are) consumed by primitive man, and therefore civilized man cannot depend upon his supply of dressed meat to furnish the dietary sufficiency which his early ancestors obtained from eating most of the animal. But this more limited nutritive value should not be interpreted as discounting the value of meat in its place.

Meat consists predominantly of protein with some fat, and a small amount of glycogen or animal sugar, as it is sometimes called. The protein consists of the important amino acids which have been shown to be necessary for the building of the body muscular tissue. Meat has about the same protein quality as milk and eggs, and is nutritionally a satisfactory supplement to the proteins of bread. Meat protein is about as digestible as that of milk and eggs.

There are large amounts of vitamin A in lambsquarters, mutton kidney, and calf and swine livers. Vitamin B is present in substantial amounts in lean pork muscle, and in small amounts in lean beef, mutton heart and kidney, and beef liver.' Vitamin G is present in substantial amounts in fresh and corned beef, pork liver and shoulder, and rabbit.' Veal, pork lean muscle, beef lean muscle, and lamb contain appreciable amounts of vitamin G, and large amounts are in beef heart, beef and veal kidney, and beef and calf livers' Some of the vitamins are lost in cooking and canning. Vitamin C in liver is mostly destroyed during cooking. There is some vitamin A and D in beef fat and mutton fat.

In general, the glandular organs are good sources of vitamins A, B, and G, and they contain some vitamin C. The muscles do not contain any appreciable amounts of the vitamins except G. McCollum makes an interesting comparison between meat and plants by showing ° that the glandular organs which are the seat of metabolic activity are more complete foods than the supporting and contractile tissues, very much like the similar relationship between the food value of the leaves of plants as contrasted with their storage tissues. The meats are about as deficient in the vitamins and minerals as the milled cereal grains, but their proteins admirably supplement those of the grains.

Cooking losses. McCance and Shipp showed that, when meats are cooked, there are two sources of loss: (a) shrinkage of tissue under the influence of heat, and (b) leaching of soluble matter by the water.

No impervious skin was formed during cooking, but the rapid evaporation of the moisture produced a similar effect and reduced the losses of soluble salts. Fat was lost mostly by reason of its liquefaction and drainage. Chatfield found 11 that the protein percentage con-tent may be increased during cooking.

Liver, eggs, and oysters can be cooked without serious effect on their content of vitamin A. The relative stability of vitamin B 1 in non-alkaline media indicates that cooked eggs, meat, and fish can be good sources of this vitamin, although there may be some destruction in the higher temperatures of canning. The slow cooking of stews and roasts is likely to cause a destruction of vitamin C, and frying has been found to be very destructive, probably due to the high temperatures reached. The presence of 1/4 to 2 percent of cooking salt retards the auto-oxidation of ascorbic acid.

Meat in the diet. There has been much controversy over the relative merits of a vegetarian versus a meat diet. The advocates of the vegetarian diet declare that the eating of meat deadens the faculties and produces waste products which bring on uric acid disorders or which have poisonous properties. Meats are generally known to be acid forming. McCollum reviewed much of the experimental evidence and showed that, whereas animals can live on a vegetarian diet, they thrive better on diets that contain some meat, particularly with small amounts of the glandular organs. Sherman stated 6 that eating meat in moderation has not been shown to be harmful, and that the question as to the advisability of its place in the diet is also an economic one.

McCollum and Simmonds examined the dietaries of numerous races of primitive and civilized man, and found that the carnivorous diet, when adequately supplemented with those nutritional factors which may be lacking, produced robust and healthy people. Controlled experiments on animals demonstrated that a diet derived solely from animal tissues can produce healthy stock, but this is possible only by skillful combinations. One of the great values of meat in the diet is its flavor and gustatory appeal, and this is no less important than calories and chemicals.

Epidemiology. It has been recognized from time immemorial that disease may be transmitted from beast to man, particularly when the animal is consumed as food. In the ancient Hebrew nation, Moses set up a sanitary code which was a forward step compared with the practices of their less-enlightened neighbors: "Ye shall not eat of any-thing that dieth of itself ; thou shall give it to the stranger that is in thy gates, that he may eat it; or thou mayest sell it unto an alien" (Deuteronomy 14:21).

The literature contains many references to epidemics traced to the consumption of unwholesome meat. German statistics are particularly full in this respect. For example, Ostertag reports in his Handbook 90 outbreaks in 23 years involving more than 4000 cases. Savage and White report 13 that, out of 92 outbreaks in England which seemed traceable to unwholesome food, 26 were caused by meat. In another report, Savage lists 128 meat outbreaks out of a total of 203. In this country, a writer in the Journal of the American Medical Association found 15 that, during the years 1923, 1924, and 1925, there were 425 recorded outbreaks of food poisoning of which 63 were charged to meat. This number does not include 10 cases charged to soup.

In general, most of these meat-borne outbreaks of illness are caused by the meat from sick animals (sometimes slaughtered as emergency measure), or by prepared meat products, such as broths, stews, sausage, and meat pies which have become infected during their manufacture or preparation. In this country, infected meat products constitute by far the more generally recognized cause.

It is generally known that, when an animal's vitality is low, the microorganisms in the bowel may invade the blood stream and thence be distributed throughout the body. Meat putrefies very soon after the animal's death. Careless dressing of such a carcass may smear intestinal contents or other infectious material over the edible portions where the microorganisms can readily proliferate on the moist surface, even at temperatures as low as 50° F. When such meat is eaten, illness is produced by the products of bacterial metabolism (such as the toxins and other toxigenic substances), or by direct infection with the viable organism. A large amount of evidence shows that animals, ill with various septic and pyemic infections, have communicated them. As thorough cooking may kill the organisms and destroy their poisonous metabolic products, the consumption of raw meat has been particularly blamed. Experience has shown, however, that even some cooked meats have been incriminated, indicating that the cooling temperatures were not sufficient to destroy the harmful agents, or that the meat was contaminated subsequent to preparation. Sometimes, even though the muscular meat of an animal is harmless, the organs are unwholesome, indicating a greater concentration of the toxic substance there.

With regard to the second type of infections, many illnesses have been ascribed to prepared meat products. The manufacture of such foods as, for example, sausage, meat loaf, meat pies, head cheese (brawn), potted meats, meat hash, stews, chopped meat, and meat salads, involves the heating of portions of the preparation, and its handling in machinery where it is subject to contamination by flies, vermin, and human carriers of harmful microorganisms, such as work-men and chefs. These infected products become particularly dangerous when they are heated to temperatures insufficient to kill the organisms and then are allowed to cool slowly or kept warm. Such treatment incubates the organisms and produces massive doses of infection. The illness is usually caused by intoxication from the poisons formed by the metabolic processes of the growing organisms. This may involve nausea, vomiting, diarrhea, giddiness, headache, and more or less prostration, but death is infrequent, and recovery is rapid. Illness occurs in about 3 to 4 hours after eating the infected food. Thorough cooking does not always destroy the toxic substances but often weakens them.

Salmonella aertrycke is the organism which seems to be most frequently encountered," although other members of this group have been involved. In horses and cattle, the Staphylococcus aureus has been associated with pathologic conditions similar to those found in human beings, and it is thought that infections from this organism may have been incriminated more times than reported, particularly in view of man's greater susceptibility to this infection than laboratory test animals. A recent bacteriological examination was made of 16,331 food animals in Germany, either emergency slaughtered or suspected of association with food poisoning."' Salmonella organisms were found in 269 (i.e., 1.65 percent). In cattle, the organisms were found mainly in the gall bladder, hepatic lymph glands, and liver; in calves they were found in the liver, hepatic glands, spleen and gall bladder; and in pigs in the gall bladder, liver, and spleen.

Clostridium botulinum was given its name from its occurrence in unwholesome sausage. It was originally discovered in ham, but the worst offenders, especially in the early outbreaks, seem to have been liver, sausages, and brine-pickled ham, although intoxications from this source have been scattered over a wide variety of meat and other food products. The actual number of such outbreaks is relatively small, and in recent years none have been recorded in this country. In some outbreaks, it has been reported that the meat was off-flavor, but in many others there were no organoleptic indications of spoilage. The organism itself is not dangerous. Jordan states that no single case of botulism in human beings has ever been traced to ingested spores. The toxin produced by its growth is very poisonous. Fortunately, it is readily destroyed by heating, and no freshly and thoroughly cooked product is dangerous from this source. Some of the other organisms of the clostridium group, for example, Clostridium novyi, can grow on muscular tissue and penetrate into the meat, causing the formation of toxic products.

Tuberculosis. In spite of the very wide prevalence of tuberculosis among food animals, constituting according to Lippmann about 50 percent of all condemnations, the flesh or muscle meat of such animals is seldom infected. The organisms can usually reach this tissue only through the blood stream, and this does not usually contain the living organism. If the carcass is well bled and if the glands related to the respective cuts show no involvement, there is no danger from eating the meat of animals which have only a localized infection and which otherwise show a generally healthy condition. However, there may be some danger by eating the glands and organs such as the liver, lungs, mesentery, udder, intestines, and other parts that are often the seats of serious infections, and which may contribute massive doses. The signs of such infection are seldom seen or recognized by the consumer. His protection is dependent on skilled inspection by trained veterinarians.

Tubercle bacilli may pass through the intestinal walls, but enormous numbers have been found, necessary to cause infection. Some authorities hold that most of the cases of lung tuberculosis were caused by the entrance of the organism through the intestines, whereas others hold that such a course is impossible. Bovine tuberculosis is practically not communicable to adults. Children contract the disease by drinking milk which contains bovine tubercle bacilli. Swine tuberculosis is usually of the avian type, to which man is not very susceptible. The disease may be contracted from meat only as the result of careless contamination or infection of the meat during slaughter and dressing, or the sale of diseased portions. Neither of these conditions can occur under federal inspection or its equivalent.

The possibility of infection from bovine tuberculosis is becoming increasingly remote by reason of the progress towards the completion of the federal-state cooperative program of tuberculosis eradication. The reduction in the incidence of tuberculosis in cattle and poultry tends to lower the prevalence of this disease in swine. Porcine tuberculosis is contracted principally by association with tuberculous poultry, by eating tuberculous carcasses, by following tuberculous cattle, and by confinement in infected feed lots. Many hogs develop the disease from eating tuberculous milk and uncooked garbage. The gradual reduction in the incidence of tuberculosis in cattle and hogs as determined from the results of autopsies at packing centers where federal meat inspection is maintained is indicated in Table XXI.

A chronic enteritis known as Johne's disease (infection with the Mycobacterium paratuberculosis) is widely prevalent among cattle in the United States, but no cases of human infection are known. The organism is not pathogenic to guinea pigs or rabbits.

Tularemia. This is an acute infectious disease caused by infection with Pasteurella tularensis (Bacterium tularense). Man becomes infected by contact of his bare hands with the raw flesh and blood of numerous kinds of wild animals, especially wild rabbits and hares, and also by the bites of blood-sucking ticks and flies which have fed on animals infected with the organism. The disease has been caused by the consumption of insufficiently cooked wild rabbit meat, by drinking

TABLE XXI

LOSSES OF CATTLE AND SWINE DUE TO TUBERCULOSES

Year Cattle Swine

% %

1916 0.53 ...

1921 0.41 1.4

1925 0.42 1.2

1930 0.19 0.8

1933 0.11 0.7

water contaminated by water rats, by skinning wild animals, and particularly by dressing wild rabbits. From 1924 to 1935 inclusive 6174 cases and 299 deaths have been reported. Inasmuch as this is a relatively newly discovered disease, it is thought that there have been many more cases never correctly diagnosed. A full discussion of the disease in man and animals has been prepared by Francis and his associates."

After an infected rabbit has been ill for 3 or 4 days, the liver (and also the spleen, bone marrow, and lungs) becomes covered with in-numerable small round spots, and the germs grow in every part of the rabbit's body including the blood and muscles. Hunters, market men, cooks, and housewives become infected when skinning or dressing wild rabbits and other wild animals. The infection enters through cuts or abrased skin on the hands. Illness develops in about 3 days, there are characteristic symptoms, and convalescence takes about 2 or 3 months.

Infected meat is made harmless by thorough cooking. If any red juice is allowed to remain about the bones, the germs remain alive. Even the fur may harbor the organism. The hands should be washed clean, and the ordinary disinfectants are effective.

Brucellosis. The malady known in this country as undulant fever is very similar to the disease long known as Malta or Mediterranean fever. All are caused by a bacterium of the genus Brucella, which is also responsible for the widely prevalent disease of cattle known as contagious abortion. The variety which infects cattle is less virulent for man than the varieties which infect goats and hogs. Undulant fever, or brucellosis as it is now called, escaped attention for many years because the symptoms are difficult. to diagnose correctly. Even acute cases are often not recognized. Important aids to a correct diagnosis are serological tests, a skin test, and preferably cultivation of the organisms from the blood or excretions, although these may fail in long, chronic cases. See more complete discussion in the Public Health Reports, 53, 1195 (1938).

It is an occupational disease to farmers, veterinarians, butchers, and slaughterhouse workers who handle infected animals and their carcasses. The organism may enter through the skin, especially if abraded. The majority of people have no direct contact with Brucellainfected animals, except by drinking their unpasteurized milk.

Parasitic infestation. In addition to infection from bacteria, man can become infested with higher forms of microbic organisms in his food. Chief among these, so far as meat is concerned, are the protozoans and the worms.

Protozoans are inhabitants of the intestinal tracts of animals and are transmitted in the feces. The extent of this transmission by food animals is uncertain, but some cases are known to have come from the accidental contamination of food with animal feces. Some of these organisms are pathogenic and cause dysentery or toxin poisoning; some seem only to aggravate other pathogenic or pathological conditions; and some seem harmless. However, the presence of any indicates contamination with filth.

The worms (or helminths) which most frequently infest man from his meat food are the cestodes (or tapeworms), and the nematodes (or roundworms).

Tapeworm& The pork tapeworm known as Taenia solium is a segmented ribbon which may exceed 12 feet in length. A sucking head and hooks attach it to the intestinal wall. The larvae or "egg" enter the hog in its drinking water, penetrate the intestinal wall, and reach the various parts of the body in the blood stream. Here they assume a cyst form, called Cysticercus cellulosae. This condition in pork is known as "measly pork." When such food is eaten by man, the cysticercus is liberated from its sac and attaches itself to the intestinal wall. Often there are no definite symptoms, but there may be heaviness, diarrhea, alternating with constipation, loss of appetite, and headache 24 Cooking kills the organism and renders the meat whole-some. The cysticerci die naturally within 21 days of the death of the host.

A similar parasite, Taenia saginata, is known as the beef tapeworm. Its path of infestation to man is by the consumption of "measly" beef.

Trichinae. The roundworm infestations of particular importance are caused by the nematode Trichinella spiralis. Infestation with this parasite, commonly known as trichinae, causes the disease trichinosis, sometimes also called trichinelliasis. There is no accurate information concerning the prevalence of this disease in the United States. Between 1842 and 1936 there have been reported 4543 cases in this country. It is thought by some to be more prevalent among the foreign population, especially the Germans and Italians, who retain their native fondness for raw and imperfectly cooked pork and pork products. In a recent study of 24 cases of trichinosis, 22 were said to have resulted from "cooked" pork, evidently not cooked "done." The tasting of uncooked sausage during its preparation or the eating of hastily cooked hamburgers consisting of a mixture of ground beef and pork may cause the disease. The most careful inspection often misses the cysts which are buried in the muscle tissue. Even careful examinations made on pigs following experimental infection with large doses of trichinae failed to reveal any symptoms that were definitely suggestive of trichinosis.'" Thorough cooking is the only sure preventive of such infestation.

Recent investigations on human cadavers has shown an incidence as high as about 15 to 25 percent in individuals who were not known to have shown clinical symptoms. McNaught and Anderson found 48 human diaphragms out of 200 infested with Trichinella spiralis 27 From a study of 300 diaphragms from cadavers, Hall and Collins 28 think that there are probably large numbers of persons in the United States who are infested with trichinae, among whom are many who have had clinical trichinosis never, however, diagnosed as such. In the New Orleans area, Sawitz found 10 trichinous cases out of 200 autopsies, and quotes Hinman as finding 7 out of 200. Sawitz also tested 200 patients in the living population by means of Bachman's skin test, and found 5 percent positive.

In an outbreak reported by Barrett and Sears 29 in Michigan, 6 cases were fatal, 33 severe, 20 moderate, and 13 mild. They state that the eosinophil count is the most useful laboratory aid to diagnosis during the early stages. Muscle tenderness and pain, likewise pro-longed diarrhea, particularly with a greenish stool which cannot other-wise be accounted for, should always call for an eosinophil count. Hobmaier and Geiger report that, during the years 1927 to 1937 in San Francisco, 212 cases with 6 deaths were traced to the foods, including 51 to pork roasts and chops, 40 to pork sausages mainly of the kind served at cocktail parties, 42 to salami, 9 to pickled pork, 9 to mettwurst, and 1 to bear meat. They state that even federal-inspected pork is unsafe so far as this infection is concerned, and that prevention of the disease in swine eliminates it as a disease of human beings. See also Spink and Augustine on a Boston outbreak.

The hog and the rat are the usual hosts, but the parasite can accommodate itself to man. The garbage-fed hog is the major factor in the spread of the infestation. The cysts enter the body in the food, and the embryo worms are liberated in the stomach. On passing into the intestines, they mature in a few days. The larvae then are carried in the blood stream to all parts of the body. After they invade a muscle, a calcified sac envelops the worm. When the meat is eaten, the capsules are dissolved, and the cycle is repeated. Schwartz found 26' that the incidence of trichina in uncooked-garbage-fed pigs was 4.41 percent; in grain-fed pigs, 0.91 percent; and in cooked-garbage-fed pigs, 0.55 percent.

In establishments operating under federal (or equal) supervision, pork products like Italian style ham, capicola, and summer sausage are made safe for consumption without cooking by the consumer. The U. S. Bureau of Animal Industry states that, inasmuch as there is no known absolutely dependable method of inspection that will certainly indicate whether muscle tissue of pork contains trichinae, all parts of any pork muscle tissue to be used in uncooked products or in prepared meats or meat food products should be heated to at least 137° F. (58° C.) in all portions of the meat or article. Also, refrigeration at temperatures no higher than 5° F. (—15° C.) for 20 to 30 days, depending on the size of the pieces and the method of storing, likewise renders the meat safe.

The United States seems to have a problem in the control of trichinosis. It has been known to be confused with other febrile diseases, especially with typhoid fever, and sometimes undulant fever, meningitis, and others. It is thought that many cases have not been diagnosed at all. It is not a rare disease.

Myiasis. Fly larvae have been found to infest the intestines, causing a condition known as myiasis. The eggs, ingested with the food, develop larvae which penetrate the intestinal walls and cause gastrointestinal upset.

Heat penetration during cooking. Cooking cannot be relied upon to sterilize meat unless care is exercised to insure thorough cooking of all the portions. Numerous tests have shown that heat penetrates meat very slowly. For example, a 10-pound ham may be boiled for several hours without the temperature at the center reaching 190° F. (88° C.). The U. S. Department of Agriculture recommends the general rule of heating 30 minutes to the pound. Tanner and Edelmann review the results of several such investigations. Of the various methods of cooking by roasting, braising, and boiling, the last is the most effective in heat penetrability.

Effect of curing on infection. Inasmuch as meats which are pre-served only by curing solutions have been particularly free from botulinus infection, it is indicated that the ingredients must inhibit toxin formation. Tanner found that the best results in preventing the development of Clostridium botulinum spores is a curing solution which contains sodium nitrate, nitrite, chloride, and cane sugar. Solutions of sodium nitrite up to 0.92 percent strength could not be relied on to prevent toxin formation. Pryer reports 36 a case of food poisoning from canned corned beef where the original infecting organism was either aertrycke or suipestifer which had produced a heat-resistant toxin. It is not known at what stage of manufacture or subsequent handling this meat became infected. Pickling does not quickly destroy disease-producing organisms. Anthrax spores, tubercle bacilli, the enteritidis bacteria, the organisms of swine erysipelas, the pyogenic staphylococci, and streptococci are slowly killed over periods ranging from several weeks to several months. Inasmuch as salt is more of an antiseptic than a germicide, curing cannot be relied upon to prevent infection. Moreover, difficulties of penetration may preclude complete lethal effects. Tanner cites the results of investigations which indicate that curing is not a safeguard against meat infected with the organisms of swine fever or with the Salmonella group, and points out that further research could be done in this field. According to Jordan, pickling and smoking do not kill the cysticerci of T. solium.

Meat spoilage. Soon after a carcass is dressed, a condition known as rigor mortis develops, the meat assuming a very stiff and firm condition. This is caused by a coagulation of the contents of the muscle fibers, and the tissues develop a slight acidity which reaches a maximum of about 0.9 percent within a few days. This is followed by a softening, the meat becoming more tender, juicy, and palatable. This change is called ripening. Usually this period runs from 2 to 6 weeks, but there is not much benefit after the second week. Ripening is autolytic in nature and, if allowed to continue uncontrolled, will progress to spoilage and putrefaction. Weinzirl has well stated the spoilage process: 37

But spoilage is a complex process. In the first place it is a souring of the meat, due to fermentation of the carbohydrates present, by aerobic, facultative and anaerobic bacteria; secondly, it is a digestion of the proteins by aerobes and facultative anaerobes without abundant evolution of sulfides; thirdly, it is the production of indol, skatol, and other vile smelling compounds by aerobic, facultative and anaerobic bacteria; and fourthly, it is putrefaction with the production of sulfides by anaerobes.

Bacterial putrefaction is induced by moisture and heat. The action begins at the surface and penetrates into the deeper parts. Malodorous substances do not always appear. Some persons prefer to eat their meat in this condition, particularly such gamy meat as deer, rabbits, and game birds. However, in many instances, debility, fever, and gastroenteritis are reported.

When meat is held in storage, it usually develops more or less mold, or "whiskers." This growth can take place at temperatures below 32° F. (0° C.). Usually the effect is entirely superficial so that the mold can be wiped off without leaving any bad effect, although sometimes a musty odor remains. The surface tissues can easily be trimmed off, and the intensity of the taint can be determined by the boiling test.

Sometimes carcasses are not properly chilled, or they may be placed too close together in the chill room, or parts of different cuts may touch each other. Such conditions induce a so-called stinking sourness. This is repulsive, and indicates unwholesome decomposition.

Bacteria may grow on meat in storage, even at temperatures below 32° F. They are usually members of the Achromobacter and the Pseudomona groups. The surface may become sour and covered with a brown slime. Sometimes bacteria develop a phosphorescence, but their effect is only superficial. They can be washed off with vinegar without harm to the meat. Phosphorescence disappears at onset of putrefaction. Some strains produce red patches and others blue.

Chilled beef deteriorates at the surface much faster than in the deeper tissues, especially if animals were healthy and were rested before slaughter and if meat was cooled properly after slaughter and dressing. The surface may reveal adverse effects of growth of slime and mold, development of rancidity in the fat, and loss of color and bloom. Storage in an atmosphere containing 40 percent carbon dioxide at 32° F. suppresses entirely growth of these fungi, and retards growth of bacteria which cause formation of slime." Rancidity in chilled beef is caused by breakdown of connective tissue by microorganisms. A concentration of 15 percent carbon dioxide at 32° F. suppresses this form of rancidity for 50 days. In practice, it has been found that in order to prevent too rapid a development of a brownish color to meat and a bleaching of fat, a compromise concentration of no more than 10 percent of carbon dioxide will keep meat free from mold and slime for 60 to 70 days at chilling temperatures.

The storage life of chilled pork, mutton, and lamb can be pro-longed in an atmosphere containing low concentrations of carbon dioxide. The ready oxidizability of bacon fat, however, requires elimination of as much oxygen as possible.

In lean meat and bacon exposed to air, the superficial layer a few millimeters thick contains dissolved oxygen, whereas, below this layer, the tissue is completely devoid of oxygen . Both hemoglobin and nitrosohemoglobin (the pigment responsible for the color of bacon) change to the brown pigment, methemoglobin, in the presence of oxygen. Both are stable in its absence. This color change occurs only in the thin superficial layer when about 60 percent of the hemoglobin has been oxidized to methemoglobin, and is not a sign of spoilage. This oxidation is very slow at a temperature of -10° C. (14° F.), more than 4 months being required for discoloration to appear. With quarters of chilled beef at -1.4° C. (29.5° F.), there is little or no discoloration from methemoglobin up to 40-45 days after killing. On-set of discoloration is closely connected with loss of moisture from the meat. At high humidities such as 99 percent at 0° C. (32° F.), exposed muscle is discolored by methemoglobin in 20 to 30 days; excessive drying darkens the meat. This darkening is increased by sodium chloride. Sodium nitrite acts on hemoglobin in the presence of oxygen to form brown or sometimes green products, but in the absence of oxygen and in the presence of a reducing agent (as for example, sodium hydrosulphite) nitrosohemoglobin alone is formed. These latter conditions prevail in the interior of muscular tissue during curing where the oxidation-reduction potential is low.

Biochemical decomposition. Much research has been undertaken to find a laboratory method to determine incipient decomposition in meat. When meat becomes unfit to eat by reason of its repugnance to the senses (organoleptic rejection), no laboratory tests are necessary to determine its condition. But there is a spoilage threshold, so to speak, where meat is undergoing decomposition which has not become organoleptically perceptible to the average person but which is evident to skilled or sensitive persons. An inspector or quality-control officer needs laboratory tests to confirm his opinion. Moreover, questions arise in commercial operations as to whether a given meat product can safely be exposed for sale, stored, or manufactured into some product without actually showing signs of decomposition or ruining a batch.

Investigators have proposed numerous tests—such as the bacterial production of hydrogen sulphide, counts of anaerobic spores and total numbers of bacteria, bacterial reduction of methylene blue, determination of amino acid, ammonia, or other nitrogenous decomposition products, measurement of the pH value, incubation in nutrient broth, and others. Research has continued, and new tests are frequently proposed. Increase in conductivity (measuring inorganic changes), and in depression of freezing point (measuring organic changes) coincide with a clearcut increase in volatile acids, indicating tissue break-down. Several workers agree that the presence of more than about 0.02 percent ammonia indicates incipient spoilage, but it appears that the history of the sample must be known. Falk and McGuire showed that more ammoniacal nitrogen is present when meat has spoiled at low temperatures than when it spoils at room temperatures (presumably augmented by autolysis). Some work has shown that there should not be more than 500-600 milligrams of amino acid nitrogen per 100 grams of meat, and that a pH value in warm meat juice of 6.3 indicates the beginning of decomposition. Taint is reported to be indicated when there is about 1 percent of free fatty acid in meat fat. Baker has discussed some of the changes which occur in the composition of meat when it is cooked and also when it deteriorates 40 In spite of the numerous researches in this field, no dependable laboratory procedure is available to measure the degree of incipient decomposition. About the best that can be done is to use several tests, as proposed by Zwilling and Sergeewa, who use a combination of the very sensitive magnesium oxide test, the benzidine test, the Nessler turbidity and color change, the bacteria count, and the organoleptic examination.

Ptomaines. For a long time it was thought that the decomposition of foods of high nitrogen content, such as cheese and meat, resulted from the breakdown of the proteins into highly poisonous bases. These were called ptomaines (see pages 43 and 198).

CONTROL MEASURES

Standards. The U. S. Department of Agriculture has adopted 42 definitions and standards for meats and the principal meat products, summarized as follows:

A. MEATS

1. Flesh. Any edible part of the striated muscle of an animal, including a mammal, fowl, fish, crustacean, mollusk, or any other animal used for food.

2. Meat. The properly dressed flesh derived from cattle, swine, sheep, or goats, sufficiently mature and in good health at the time of slaughter but restricted to that part of the striated muscle which is skeletal or that which is found in the tongue, diaphragm, heart, or esophagus, and does not include that found in the lips, snout or ears, with or without the accompanying fat, and the portions of the bone, skin, sinew, nerve, and blood vessels which normally accompany the flesh.

3. Fresh meat. Meat which has undergone no substantial change in character since slaughter.

4. Beef. Meat derived from cattle nearly 1 year of age or older.

5. Veal. Meat derived from young cattle 1 year or less of age.

6. Mutton. Meat derived from sheep nearly 1 year of age or older.

7. Lamb. Meat derived from young sheep 1 year or less of age.

8. Pork. Meat derived from swine.

9. Venison. Flesh derived from deer.

B. MEAT BYPRODUCTS

Meat byproducts. Any properly dressed edible parts, other than meat, which have been derived from the carcasses of cattle, swine, sheep, or goats, sufficiently mature and in good health when slaughtered.

C. PREPARED MEATS

1. Prepared meat. The product obtained by subjecting meat to a process of comminuting, drying, curing, smoking, cooking, seasoning, or flavoring.

2. Cured meat. The product obtained by subjecting meat to a process of salting, by the employment of dry common salt or brine, with or without the use of one or more of the following: sodium nitrite, sodium nitrate, potassium nitrate, sugar, dextrose, a sirup, honey, spice.

3. Dry salt meat. The prepared meat, cured as above, with or without the injection into it of a solution of common salt to which may have been added one or more of the following: sodium nitrate or nitrite, potassium nitrate, sugar, dextrose, a sirup, honey.

4. Corned meat. The prepared meat which has been cured by soaking in, with or without injecting into it, a solution of common salt, with or without one or more of the following in proper proportion: sodium nitrite, sodium nitrate, potassium nitrate, sugar, dextrose, a sirup, honey, and with or without the use of spice.

5. Sweet pickled meat. The prepared meat which has been cured by soaking in, with or without injecting into it, a solution of common salt, with sugar, dextrose, sirup, or honey, together with one or more of the following: sodium nitrite or nitrate, potassium nitrate, spice.

6 Dried meat. The product obtained by subjecting fresh meat or cured meat to a process of drying, with or without the aid of artificial heat.

7. Smoked meat. The product obtained by subjecting fresh meat, dried meat, or cured meat to smoke either of burning wood or similar burning material.

8. Canned meat. Fresh or prepared meat, packed in hermetically sealed containers, with or without subsequent heating for the purpose of sterilization.

9. Hamburg steak, "Hamburger steak." Comminuted fresh beef, with or without the addition of suet or seasoning.

10. Potted meat, deviled meat. The product obtained by comminuting and cooking fresh meat and/or prepared meat, with or without spice.

11. Sausage meat. Fresh or prepared meat or a mixture of them, sometimes comminuted. Sometimes the term is applied to bulk sausage containing no meat byproducts.

D. MEAT FOOD PRODUCTS

1. Meat food products. Any articles of food or any articles that enter into the composition of food which are not prepared meats but which are derived or prepared, in whole or in part, by a process of manufacture from any portion of the carcasses of cattle, swine, sheep or goats, if such manufactured portion be all or a considerable portion of the article, except such preparations which are for medicinal purposes only.

2. Meat loaf. The product consisting of a mixture of comminuted meat with spice and/or cereals, with or without milks and/or eggs, pressed into the form of a loaf and cooked.

3. Pork sausage. Chopped or ground fresh pork, with or without one or more of the following: herbs, spice, common salt, sugar, dextrose, a sirup, water.

4. Brawn. The product made from chopped or ground and cooked edible parts of swine, chiefly from the head, feet, and/or legs, with or without the chopped or ground tongue.

5. Headcheese, mock brawn. The product made from chopped or ground, cooked edible parts of meat or meat byproducts.

6. Souse. The product consisting of meat and/or meat byproducts; after cooking the mixture is commonly packed into containers and covered with vinegar.

7. Scrapple. The product consisting of meat and or meat byproducts mixed, with meal or the flour of grain, and cooked with seasoning materials, after it is poured into a mold.

E. LARD

1. Lard. The rendered fresh fat from hogs in good health when slaughtered. It is free from rancidity and contains not more than 1 per cent of substances other than fatty acids and fat.

2. Leaf lard. Lard rendered at moderately high temperatures from the internal fat of the abdomen of the hog, excluding that adherent to the intestines, and having an iodine number not greater than 60.

3. Neutral lard. Lard rendered at low temperatures.

Detailed instructions are published by the U. S. Department of Agriculture for the direction of its field inspection staff. Municipalities which have effective meat inspection also usually publish their respective rules and regulations which are founded to a greater or less extent on those of the federal government.

Types of adulteration and unwholesomeness encountered. Meat may come from diseased animals, or may have undergone spoilage from lack of proper refrigeration. However, some meat has been thought to be spoiled as judged by its odor whereas this may be only a strong sexual odor, somewhat obnoxious but no indication of unwholesomeness. Mold, bacteria, or insect larvae may infect and infest it respectively. Ground fresh meat may contain undeclared preservatives and colors. Prepared meat products may contain ingredients which are not recognized in the standards. Canned meat may contain grades inferior to the label declarations, or it may have been prepared under conditions at variance with the official regulations and therefore be subject to regulatory action.

Physical tests. Dressed meat from diseased animals can some-times be identified by adhering parts of untrimmed glands, or by the absence of tissues that ordinarily are not trimmed, indicating that the butcher has removed some telltale evidence of unwholesomeness. A keen sense of smell will often indicate incipient spoilage or contamination with unclean fluids. This is facilitated by thrusting a clean skewer into the meat, especially for deep-seated taints, and smelling it quickly when withdrawn. Chopped meat of particularly red color indicates possible use of chemical preservatives.

Canned meats are judged by the appearance of the cans. A properly packed can is under a partial vacuum which keeps the ends drawn in or concave. When such a can is sharply tapped, it emits a dull sound; when pressed, it does not feel springy. When the contents spoil with formation of gas, the ends bulge and become convex. On tapping, the can emits a ringing or sharp metallic note. Sometimes the contents may spoil without the formation of gas, or a perforation may allow the gas to escape. Any perforated or imperfectly sealed can or one that is abnormal in any way may be an actual or a potential health hazard.

Detection of trichina larvae. Bozicevich collects larvae by digesting infested meat with a digestive fluid prepared by adding 15 grams of pepsin to 3 liters of warm tap water, later acidulated with 21 milliliters of hydrochloric acid. The digestive fluid is placed in a large funnel whose stem is rubber-connected to a glass tube. The meat to be examined is placed in the digestive fluid in the funnel, and incubated at 37° C. As the larvae are liberated, they gravitate to the tube.

Odors. The odors, indicative of incipient decomposition as well as those of sexual origin, can be accentuated by quickly dropping a minced sample into a small beaker of water that is already boiling, and smelling them in the steam.

Chemical tests. Sample. Fresh meats are separated as completely as possible from bone, passed through a food chopper 3 times with thorough mixing, and analyzed immediately. Canned meat from the entire can is passed through the chopper as above. Sausage is freed from its casing and chopped likewise.

Moisture. The sample is dried in a covered dish to constant weight in a vacuum desiccator over freshly heated sulphuric acid.

Water in sausage. A sample of about 7 grams is dried in a wide weighing bottle by heating at atmospheric pressure at a temperature of 101-102° C. for 16-18 hours, or of 125° C. for 2-3 hours, or to constant weight in a vacuum desiccator. The added water is calculated by multiplying the percentage of protein (N X 6.25) by 4, and subtracting the result from the percentage of moisture found.

Added starch. The presence of added starch in chopped meat, sausage, deviled meat, and other such products is shown by the typical blue coloration of the reaction of starch with iodine .6 However, traces of starch may be due to the spices used. Microscopic examination may indicate the kind of starch. The starch can be determined quantitatively by digesting the meat in alcoholic potassium hydroxide, then acidifying with sulphuric acid, clearing the solution, and deter-mining the formed dextrose with cuprous oxide. The weight of the dextrose, multiplied by 0.9, gives the weight of the starch.

The addition of soybean flour to sausage is shown by the liberation of ammonia by urease, or, when the enzyme is destroyed by the previous heating of the flour, by microscopic identification of the soybean cells. The detection of added skim-milk powder is based on the conversion of lactose to lactose osazone and its identification by melting-point determination.

Color pigments in meat can be detected by extracting a sample with 50 percent alcohol, and identified by specific color reactions.

Nitrites are identified 48 by extracting about 5 grams of the sample with water, treating with saturated mercuric chloride, making up to 500 milliliters, filtering, and determining the amount of preservative colorimetrically in a Nessler tube against a standard sample.

Sulphites may be formed by the decomposition of the meat itself 48 so that the presence of small amounts may be no indication that they have been added.

Benzoates are determined by identification of the benzoic acid crystals from an ether extract. Salicylates are identified by the purple color reaction between ferric chloride and the dry residue from the ether extraction.

Decomposition. Meat that is spoiled does not need a laboratory test to prove it. There is a need for a test to determine incipient decomposition, but none has been devised which clearly shows this. Numerous chemical and bacteriological tests have been recommended, but all have only a limited significance.

Bacteriological examination. A sample of a meat product may be treated for plating on nutrient agar and counting the number of colonies, or for counting the organisms directly. In the former, the outside of the product is sterilized by quickly passing it through a flame, opening it with a sterile knife, and removing several grams, emulsifying or suspending it in sterile water in a shaking machine or ball mill, and plating out on nutrient agar. Bickert stains this suspension and counts the ogranisms in a blood-counting chamber. The use of a tetrathionate broth as an enrichment medium has been reported to favor the development of the greatest number of organisms associated with food poisoning. For the bacteriological examination of meat pastes, a medium made from skimmed milk with a bromo-cresol purple indicator has been recommended for the detection of anaerobes in 3 to 4 days incubation at 37° C.5°

For the examination of canned meat, see directions on pages 445-448. Supervisory procedure. The meat-inspection service of the U. S. Department of Agriculture requires that all meat and meat products that are distributed in interstate commerce, produced in the territories or the District of Columbia, or imported into this country, must be packed in establishments under license by the Secretary of Agriculture. Any house may obtain this service without charge, provided that it complies with the official regulations. These stipulate that the premises and building be made sanitary, that proper equipment be installed to enable the inspectors to supervise the slaughter of the animals and the dressing of the meat, and that all operations, including the disposal of the wastes and condemned parts, be handled in accordance with the regulations. Licenses are subject to cancellation for cause. Every interstate carrier of meat and meat products must have a certificate from the shipper that the lading has been "U. S. Inspected and Passed by Department of Agriculture." The possibility that products may spoil after leaving the packing house requires the extension of inspection to meat in storage and during transportation.

Some municipalities have inaugurated meat-inspection services modeled on the federal system. However, most of them operate under a totally inadequate and casual round of occasional visits to abattoirs and meat-handling establishments—a practice which keeps only a small percentage of unwholesome meat off the market. The average butcher is not trained to detect the many symptoms of disease and evidences of pathological conditions. With the very best intentions of performing a conscientious public service, he may miss conditions which a trained veterinarian-inspector would detect immediately, though even he may be misled unless he examined the animal on the hoof.

The procedure followed in effective supervision is to examine all animals for healthfulness before slaughter, then inspect all organs, palpate the fleshy parts to ascertain their condition, open lymph glands, squeeze out contents of passages and sacs, and examine doubtful parts by adequate laboratory tests. Intelligent and final judgment of the fitness of meats for human consumption is based largely on conditions found in lymph glands.

Packing-house employees themselves should be free from communicable disease. The plant should be kept in a clean, sanitary condition, including provision of a pure water supply and adequate toilet facilities, proper disposal of waste, protection from vermin infestation, and the practice of good housekeeping. Proper supervision also re-quires correct and safe processing, enforces the use of clean practices, prevents use of harmful colors and preservatives, and insures correct labeling.

Samples of products suspected of contamination, adulteration, or unwholesome deterioration should be sent to the laboratory for detailed examination, especially canned meat, sausage, chopped meats, mincemeat, and other prepared products. Great care is necessary in the examination of canned meats, as evidenced by the irregularity with which Savage reports that spoiled products were detected.

The City of San Francisco has inaugurated regulatory control of trichinosis 52 by requiring that all garbage-fed hogs received into the city must come from hog ranches which possess a permit from the health authorities, requiring that premises be kept sanitary, that all buildings be effectively rat-proofed, and that all garbage be pasteurized before feeding it to hogs.

It has been argued that the cost of effective meat control by ante-and post-mortem inspection does not yield the public-health benefits that could be obtained by spending less money for other services, particularly nursing. However, the public expects its food to be clean and wholesome, just as it expects the streets and pavements to be cleaned, even though the cost of the latter service may be greater than some more direct health measure. The health departments are usually staffed and experienced in administering food control, and it is reasonable that they should constitute the official agency for this meat-inspection service.

REFERENCES

1. Editorial, Am. J. Pub. Health, 23, 604 (1933).

2. U. S. Dept. Agr. M. I., 124, 1934.

3. C. R MOULTON, Meat through the Microscope, University of Chicago Press, 1929, pp. 209 et seq.

4. W. O. ATWATER and A. P. BRYANT, U. S. Dept. Agr. Office of Exp. Sta. Bul. 28, revised, 1906.

5. R. HOAGLAND, U. S. Dept. Agr. Circular 230, 1932.

6. H. C. SHERMAN, Food Products, Macmillan, New York, 3d ed., 1933, p. 229.

7. E. R. DANIEL and H. E. MuNSELL, U. S. Dept. Agr. Misc. Pub. 275, 1937.

8. W. H. SEBRF.T.T,, U. S. Pub. Health Repts., 49, 754 (1934).

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11. C. CHATFIELD, J. Am. Diet. Assoc., 13, 312 (1937).

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30. M. HOBMAIER and J. C. GEIGER, ibid., 28, 1202 (1938).

31. W. W. SPINE and D. L. AUGUSTINE, New England J. Med., 213, 527 (1935).

32. M. C. HALL, Pub. Health Repts., 52, 873 (1937) ; 53, 1086 (1938).

33. Service and Regulatory Announcements, U. S. Dept. Agr. Bur. Animal Ind. 359, March, 1937.

34. F. W. TANNER, The Microbiology of Foods, Twin City Printing Co., Champaign, Ill., 1932.

35. R. EDELMANN, J. R. MOHLER, and A. EICHHORN, Meat Hygiene, Lea & Febiger, Philadelphia, 5th ed., 1925; (a) p. 450.

36. R. W. PRYER, Am. J. Pub. Health, 19, 208 (1929).

37. C. R. FELLERS, A. C. HUNTER, and F. A. KoRFF, ibid., 389.

38. T. MoRAN, J. Food Research, 3, 149 (1938).

39. J. BROOKS, ibid., 75.

40. L. C. BAKER, J. Soc. Chem. Ind., 54, 154T (1935).

41. A. ZWILLING and M. SERGEEWA, Z. Ureters. Lebensm., 72, 148 (1936), from Chem. Abs., 31, 1898 (1937).

42. Service and Regulatory Announcements, U. S. Dept. Agr., Food and Drug 2, 5th revision, November, 1936.

43. Bureau of Animal Industry, U. S. Dept. Agr., Order 211, revision issued Dec. 2, 1922, with amendments.

44. W. H. FELDMAN, J. Infectious Diseases, 59, 43 (1936).

45. W. G. SAVAGE, "Part I. Canned Meats," Dept. Sci. Ind. Research, Food Investigation Board, Spec. Rept. 3, 1920.

45a. J. BozICEvICH, Pub. Health Repts., 53, 2130 (1938).

46. Methods of Analysis, 4th ed., Association of Official Agricultural Chemists, 1935; (a) p. 357.

47. R. H. KERR, J. Assoc. Offic. Agr. Chemists, 19, 409 (1936).

48. A. E. LEACH and A. L. WINTON, Food Inspection and Analysis, John Wiley & Sons, New York, 4th ed., 1931.

49. F. W. BICKERT, Z. Untersuch. Lebensm., 59, 345 (1930), from Chem. Abs., 24, 5889 (1930) ; TANNER, reference 34, p. 494.

50. E. L. CROSSLEY, J. Hygiene, 38, 205 (1938).

5L J. S. BUCKLEY, U. S. Dept. Agr. Circular 32, 1928.

52. San Francisco Department of Public Health, Executive Order 209, revised, March 15, 1938; revised, Oct. 7, 1938.

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